As we know Mobile Ad hoc networks (MANET) and Peer-to-Peer (P2P) networks share central characteristics such as their distributed and decentralized nature. Mobile Ad hoc Networks (MANETs) and Peer-to-Peer (P2P) networks share concepts of self-organization and decentralization. Both systems operate without a central, coordinating entity and do not require a preexisting communication infrastructure for operation. Combining both networking paradigms results in a Mobile Peer-to-Peer (MP2P) system that operates independently from a preexisting infrastructure. Securing MP2P networks in terms of availability and robustness as basic demands in envisioned application scenarios like first responder operations is a challenging task. In this paper, we present a review of architectures, challenges and attacks in these networks.